The method of the present invention is especially adaptable for use in producing that type of rotary rock bit popularly known as a three cone bit; however, it is not restricted thereto and the method of the present invention can be used for constructing bearings that can be used in other equipment wherein an improved bearing system is required. In order to obtain high penetration rates with a rotary rock bit in some formations, it is necessary to apply heavy loads on the bit and to operate the bit at a moderate speed. With other formations only moderate loads are required, but the bit must be operated at relatively high speeds.
The rotary rock bit operates under a high corrosive environment and is subjected to temperature extremes. The drilling operation is often conducted thousands of feet underground wherein elevated temperatures are encountered. The bit is continually flushed by circulating drilling fluid to cool the bit and carry away the drill cuttings. This fluid is generally water with chemicals added to control water loss or to control viscosity and/or Ph. These chemicals may produce a corrosive drilling fluid. The drill cuttings, the materials encountered in the earth formations, barites added for fluid weight control, and the chemical composition of the drilling fluid combine to create a corrosive and abrasive drilling environment.
In view of the previously explained circumstances, it can be appreciated that a bearing system for a rotary rock bit must be constructed so that it will include exceptional performance characteristics within a limited geometrical configuration. Since the entire drill string must be withdrawn to replace a bit should it fail, it is highly desirable to have the bearing systems of the bit operate for an extended period of time.